The present invention relates generally to a drive circuit for a wiper device for cleaning a vehicle windshield, wing mirrors of an automotive vehicle and so on. More specifically, the present invention relates to a wiper device drive circuit which is adapted to drive a pair of wiper assemblies in synchronism with each other.
Conventionally, automotive vehicle wiper devices include a crank mechanism and linkage for connecting the crank mechanism to a driving motor. The crank mechanism is adapted to transmit the driving power of the motor to the wiper assembly to reversibly drive the same. A pair of wiper assemblies are provided for cleaning or wiping the automotive windshield. The crank mechanism is connected to the wiper assemblies to drive the latter in synchronism with each other.
Recently, developed wiper assemblies are directly connected to reversible drive motors for reducing the size thereof. In such wiper system, the drive motors are controlled electrically to reverse the driving direction by respective control circuits. The wiper systems of this type are applicable to the front windshield wiper as well as to head lamp and the wing mirror wipers. Since the head lamp or the wing mirror wipers must be compact enough to be located in relatively small spaces, the electrically controlled wiper system is useful. On the other hand, each pair of windshield or wing mirror wipers must be synchronously driven. However, there is a tendency for the motion of each wiper in an assembly of a pair of wipers to differ due to differences of electric response characteristics of the driving circuits.
This necessarily degrades driving comfort and sometimes requires the driver to manually adjust the wiper motion during driving.
An object of the present invention is to provide a wiper drive circuit which can eliminate the drawback in the prior art.
It is another object of the present invention to provide a wiper device drive circuit, which is capable of driving a pair of wiper blades in synchronism with one another and has simple and low cost circuit construction.